The Letter Of Petrus Peregrinus On The Magnet, A.D. 1269. INTRODUCTORY. The magnetic lore of classic antiquity was scanty indeed, being limited to the attraction which the lodestone manifests for iron. Lucretius 99-55 B. C., however, in his poetical dissertation on the magnet, contained in Arrtura, Book VI. recognizes magnetic repulsion, magnetic induction, and to some extent the magnetic field with its lines of force, for in verse 40 he writes Oft from the magnet, too, the steel recedes, Repelled by turns and re-attracted close...